Wireless device discovery in a wireless peer-to-peer network

ABSTRACT

Systems and methodologies are described that facilitate detecting and/or identifying peers in a local area peer-to-peer network. Times (e.g., peer discovery intervals) for performance of mutual detection and identification between peers may be synchronized (e.g., based upon a signal broadcast to the peers), Further, within each partitioned peer discovery interval, a wireless terminal may select a portion of time to transmit (e.g., broadcast) short messages that may be employed by peers to detect and/identify the wireless terminal. Moreover, the remainder of the time within the partitioned peer discovery interval may be employed to listen to short messages received from peers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patentapplication Ser. No, 60/758,010 entitled “METHODS AND APPARATUS FORFACILITATING IDENTIFICATION, SYNCHRONIZATION OR ACQUISITION USING BEACONSIGNALS” which was filed Jan. 11,2006; U.S. Provisional Patentapplication Ser. No. 60/758,011 entitled “METHODS AND APPARATUS FORUSING BEACON SIGNALS FOR IDENTIFICATION, SYNCHRONIZATION OR ACQUISITIONIN AN AD HOC WIRELESS NETWORK” which was filed Jan. 11, 2006; U.S.Provisional Patent application Ser. No. 60/758,012 entitled “METHODS ANDAPPARATUS FOR USING BEACON SIGNALS IN A COGNITIVE RADIO NETWORK” whichwas filed Jan. 11, 2006; U.S. Provisional Patent application Ser. No.60/845,052 entitled “POWER ALLOCATION SCHEME” which was filed Sep. 15,2006; U.S. Provisional Patent application Ser. No. 60/845,051 entitled“BEACONS IN A MIXED WIRELESS COMMUNICATION SYSTEM” which was filed Sep.15,2006; and U.S. Provisional Patent application Ser. No. 60/863,304entitled “BEACONS IN A MIXED COMMUNICATION SYSTEM” which was filed Oct.27, 2006. The entireties of the aforementioned applications are hereinincorporated by reference.

BACKGROUND

I. Field

The following description relates generally to wireless communications,

and more particularly to enabling peers to discover and identify eachother in a peer-to-peer network.

II. Background

Wireless communication systems are widely deployed to provide varioustypes of communication; for instance, voice and/or data may be providedvia such wireless communication systems. A typical wirelesscommunication system, or network, can provide multiple users access toone or more shared resources. For instance, a system may use a varietyof multiple access techniques such as Frequency Division Multiplexing(FDM), Time Division Multiplexing (TDM), Code Division Multiplexing(CDM), Orthogonal Frequency Division Multiplexing (OFDM), and others.

Common wireless communication systems employ one or more base stationsthat provide a coverage area. A typical base station can transmitmultiple data streams for broadcast, multicast and/or unicast services,wherein a data stream may be a stream of data that can be of independentreception interest to a wireless terminal. A wireless terminal withinthe coverage area of such base station can be employed to receive one,more than one, or all me data streams earned by the composite stream.Likewise, a wireless terminal can transmit data to the base station oranother wireless terminal.

Wireless communication systems leverage various portions of wirelessspectrum for transferring data. However, wireless spectrum is anexpensive and valuable resource. For example, significant coats may beincurred by a company desiring to operate a wireless communicationsystem over a portion of the wireless spectrum (e.g., within thelicensed spectrum). Further, conventional techniques typically provideinefficient utilization of wireless spectrum. According to a commonillustration, the spectrum allocated for wide area network cellularcommunication oftentimes is not uniformly utilized across time andspace; thus, a significant subset of spectrum may be unused in a givengeographic location or in a given time interval.

According to another example, wireless communication systems oftentimesemploy peer-to-peer or ad hoc architectures whereby a wireless terminalmay transfer signals directly to another wireless terminal. As such,signals need not traverse through a base station; rather, wirelessterminals within range of each other may discover and/or communicatedirectly. However, conventional peer-to-peer networks typically operatein an asynchronous manner whereby peers may effectuate differing tasksat a particular time. Consequently, peers may encounter difficultyassociated with identifying and/or communicating with disparate peerswithin range, power may be inefficiently utilized, and so forth.

SUMMARY

The following presents a simplified summary of one or more embodimentsin order to provide a basic understanding of such embodiments. Thissummary is not an extensive overview of all contemplated embodiments,and is intended to neither identify key or critical elements of allembodiments nor delineate the scope of any or all embodiments. Its solepurpose is to present sonic concepts of one or more embodiments in asimplified form as a prelude to the more detailed description that ispresented later.

In accordance with one or more embodiments and corresponding disclosurethereof, various aspects are described in connection with facilitatingdetection and/or identification of peers in a local area peer-to-peernetwork. Times (e.g., peer discovery intervals) for performance ofmutual detection and identification between peers may be synchronized(e.g., based upon a signal broadcast to the peers). Further, within eachpartitioned peer discovery interval, a wireless terminal may select aportion of time to transmit (e.g., broadcast) short messages that may beemployed by peers to detect and/identify the wireless terminal.Moreover, the remainder of the time within the partitioned peerdiscovery interval may be employed to listen to short messages receivedfrom, peers.

According to related aspects, a method of operating a first wirelessterminal in a peer-to-peer network is described herein. The method mayinclude receiving a first signal from a signal source wherein the signalsource is at least one of a base station, an access node, or a GPSsatellite. Further, the method may comprise determining time positionsof a first sequence of peer discovery intervals based upon the receivedfirst signal.

Another aspect relates to a wireless communications apparatus. Thewireless communications apparatus may include a memory that retainsinstructions related to obtaining a first signal from a signal sourceand identifying time positions of a first sequence of peer discoveryintervals based upon the obtained first signal. Further, the wirelesscommunications apparatus may include a processor, coupled to the memory,configured to execute the instructions retained in the memory.

Yet another aspect relates to a wireless communications apparatus thatenables synchronizing a time period for discovery of peers in apeer-to-peer network. The wireless communications apparatus may includemeans for receiving a first signal from a signal source; and means forlocating time positions of a first sequence of peer discovery intervalsbased upon the first signal.

Still another aspect relates to a machine-readable medium having storedthereon machine-executable instructions for obtaining a first signalfrom a base station, and determining time positions of a sequence ofpeer discovery intervals as a function of the obtained first signal, thesequence being synchronized with disparate sequences of peers in apeer-to-peer network based upon the obtained signal.

In accordance with another aspect, an apparatus in a wirelesscommunication system may include a processor, wherein the processor maybe configured to obtain a periodic signal from a base station.Additionally, the processor may be configured to identify time positionsof a sequence of peer discovery intervals based upon the obtainedperiodic signal, wherein the sequence of peer discovery intervals issynchronized between peers of a peer-to-peer network.

To the accomplishment of the foregoing and related ends, the one or moreembodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspects ofthe one or more embodiments. These aspects are indicative, however, ofbut a few of the various ways in which the principles of variousembodiments may be employed and the described embodiments are intendedto include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a wireless communication system inaccordance with various aspects set forth herein.

FIG. 2 is an illustration of an example system that synchronizescommunication between wireless terminals in a peer-to-peer network.

FIG. 3 is an illustration of an example timing diagram utilized bysynchronized peers communicating within a peer-to-peer environment.

FIG. 4 is an illustration of an example timing diagram of a peerdiscovery interval,

FIG. 5 is an illustration of an example system that effectuatessynchronized communications over a peer-to-peer network.

FIG. 6 is an illustration of an example time-frequency grid associatedwith transmission during a peer discovery interval.

FIG. 7 is an illustration of an example methodology that facilitatesoperating a wireless terminal in a peer-to-peer network,

FIG. 8 is an illustration of an example methodology that facilitatestransmitting a message that enables peers to detect and identify awireless device in a peer-to-peer network.

FIG. 9 is an illustration of an example methodology that, facilitatesdetecting and identifying peers in a peer-to-peer network.

FIG. 10 is ah illustration of an example communication systemimplemented in accordance with various aspects including multiple cells.

FIG. 11 is an illustration of an example base station in accordance withvarious aspects.

FIG. 12 is an illustration of an example wireless terminal (e.g., mobiledevice, end node, . . . ) implemented in accordance with various aspectsdescribed herein.

FIG. 13 is an illustration of an example, system that enablessynchronizing a time period for discovery of peers in a peer-to-peernetwork.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more embodiments. It may be evident, however,that such embodiment(s) may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component may be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal).

Furthermore, various embodiments are described herein in connection witha wireless terminal. A wireless terminal can also be called a system,subscriber unit, subscriber station, mobile station, mobile, mobiledevice, remote station, remote terminal, access terminal, user terminal,terminal, wireless communication device, user agent, user device, oruser equipment (UE). A wireless terminal may be a cellular telephone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, computing device,or other processing device connected to a wireless modem. Moreover,various embodiments are described herein in connection with a basestation. A base station may be utilized for communicating with wirelessterminal(s) and may also be referred to as an access point, Node B, orsome other terminology.

Moreover, various aspects or features described herein may beimplemented as a method, apparatus, or article of manufacture usingstandard programming and/or engineering techniques. The term “article ofmanufacture” as used herein is intended to encompass a computer programaccessible from any computer-readable device, carrier, or media. Forexample, computer-readable media can include but are not limited tomagnetic storage devices (e.g., hard disk, floppy disk, magnetic strips,etc.), optical disks (e.g., compact disk (CD), digital versatile disk(DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card,stick, key drive, etc.). Additionally, various storage media describedherein can represent one or more devices and/or other machine-readablemedia for storing information. The term “machine-readable medium” caninclude, without being limited to, wireless channels and various othermedia capable of storing, containing, and/or carrying instruction(s)and/or data.

Referring now to FIG. 1, a wireless communication system 100 isillustrated in accordance with various embodiments presented herein.System 100 may comprise one or more wireless terminals 102. Although twowireless terminals 102 are depicted, it is to be appreciated that system100 may include substantially any number of wireless terminals 102.Wireless terminals 102 can be, for example, cellular phones, smartphones, laptops, handheld communication devices, handheld computingdevices, satellite radios, global positioning systems, PDAs, and/or anyother suitable device for communicating over wireless communicationsystem 100. Wireless terminals 102 can communicate directly with eachother via a local area peer-to-peer (P2P) network (e.g., ad hocnetwork). Peer-to-peer communication may be effectuated by directlytransferring signals between wireless terminals 102; thus, the signalsneed not traverse through a base station (e.g., base station 104). Thepeer-to-peer network may provide short range, high data ratecommunication (e.g., within a home, office, etc. type setting).

Further, system 100 may support, a wide area network (WAN). System 100may include a base station 104 (e.g., access point) and/or any number ofdisparate base stations (not shown) in one or more sectors that receive,transmit, repeat, etc. wireless communication signals to each otherand/or to one or more wireless terminals 102. Base station 104 cancomprise a transmitter chain and a receiver chain, each of which can inturn comprise a plurality of components associated with signaltransmission and reception (e.g., processors, modulators, multiplexers,demodulators, demultiplexers, antennas, . . . ) as will be appreciatedby one skilled in the art. Wireless terminal(s) 102 may transmit signalsto and/or receive signals from base station 104 when communicating viathe wide area infra-structure network supported by system 100.

Peer-to-peer communication between wireless terminals 102 may besynchronous. For example, wireless terminals 102 may utilize a commonclock reference to synchronize performance of distinct functions.Wireless terminals 102 may obtain timing signals from base station 104(and/or a transmitter (not shown) that provides less functionality)utilized to synchronize operation of wireless terminals 102. Wirelessterminal 102 may obtain timing signals from other sources, such as GPSsatellites. According to an illustration, time may be meaningfullypartitioned in a peer-to-peer network for functions such as peerdiscovery, paging, and traffic. Further, it is contemplated that eachpeer-to-peer network may set its own time,

Before communication in a peer-to-peer network can take place, wirelessterminals 102 (e.g., peers) may detect and identify each other. Theprocess by which this mutual detection and identification between peerstakes place may be referred to as peer discovery. System 100 may supportpeer discovery by providing that peers desiring to establishpeer-to-peer communication periodically transmit short messages andlisten to the transmissions of others.

Transmissions for peer discovery may periodically occur during specifiedtimes referred to as peer discovery intervals, the timing of which maybe predetermined by a protocol and known to wireless terminals 102.Peers may be synchronized to a common clock reference. For example,wireless terminals 102 may decode a small amount of broadcastinformation from locally positioned base station 104. Synchronizationmay allow for peers in a given geographic location to recognize a startand a finish of each discovery interval.

The local area peer-to-peer network and the wide area network may sharea common wireless spectrum to effectuate communication; thus, bandwidthmay be shared for transferring data via the disparate types of networks.For example, the peer-to-peer network and the wide area network may bothcommunicate over the licensed spectrum. However, the peer-to-peercommunication need not utilize the wide area network infrastructure.

Now turning to FIG. 2. illustrated is a system 200 that synchronizescommunication between wireless terminals in a peer-to-peer network.System 200 includes a wireless terminal 202 that communicates directlywith substantially any number of disparate wireless terminals (e.g.,disparate wireless terminal 1 204, . . . , disparate wireless terminal X206, where X may foe any integer). Although the following providesfurther detail with regards to wireless terminal 202, it is to beappreciated that such illustrations may similarly apply to disparatewireless terminals 204-206.

Wireless terminal 202 may further include a synchronizer 208 thatconforms timing between wireless terminal 202 and disparate wirelessterminals 204-206. Synchronizer 208 may obtain its timing from a commonclock reference. Similar synchronizers (not shown) of disparate wirelessterminals 204-206 may obtain their respective timing from the samecommon clock reference. Further, synchronizer 208 may utilize apredetermined protocol to evaluate the common clock reference toidentify a type of function to be effectuated at the time associatedwith the common clock reference (e.g., current time). Thus, for example,synchronizer 208 and similar synchronizers (not shown) of disparatewireless terminals 204-206 may determine that a time period identifiedfrom the common clock reference may be employed for one of peerdiscovery, paging, or traffic. The time period identified will besubstantially the same or similar for synchronizer 208 and similarsynchronizers (not shown) of disparate wireless terminals 204-206, eventhough wireless terminals 202-206 have not directly communicate witheach other.

The common clock reference utilized by synchronizer 208 may be broadcastinformation from a base station (not shown) in a vicinity of wirelessterminal 202 and disparate wireless terminals 204-206. Another commonclock reference may include GPS satellite signals, For example, thebroadcast information may be a Beacon, a PN (pseudo random) sequencesignal, a pilot signal or other broadcast signal. Further, the broadcastsignal may be periodically received from the base station. Moreover,timing information may be determined from the broadcast signal bysynchronizer 208. By way of illustration, wireless terminal 202 anddisparate wireless terminals 204-206 may receive and synchronize to thesame broadcast signal, and therefore, have a common understanding oftime. The common notion of time may be utilized to partition a timelineinto distinct periods for each type of function (e.g., peer discovery,paging, traffic) according to a predetermined pattern defined by the airinterface protocol.

Additionally, wireless terminal 202 may include a peer discoverycommunicator 210 that effectuates peer discovery during a peer discoveryinterval as determined by synchronizer 208. Peer discovery communicator210 may further comprise a signal broadcaster 212 and a peer detector214. Signal broadcaster 212 may transmit a message, in a first portionof the peer discovery interval, to disparate wireless terminals 204-206that enables disparate wireless terminals 204-206 to detect and identifywireless, terminal 202. Further, in a second portion of the peerdiscovery interval, peer detector 214 may receive message(s) sent fromdisparate wireless terminal(s) 204-206; peer detector 214 may analyzethe received message(s) to detect and identify disparate wirelessterminal(s) 204-206 to which the message(s) correspond. In someembodiments, the first and the second portions of the peer discoveryinterval may not overlap in time. Further, a transmit/receive switchguard time may be reserved between the first and the second portions ofthe peer discovery interval.

By way of example, wireless terminal 202 may enter into a peer-to-peernetwork that includes disparate wireless terminal 1 204 and disparatewireless terminal X 206. Upon entering the network, synchronizer 208 maydetermine timing associated with peer-to-peer communications (e.g.,based upon a received common clock reference). Further, at a timepartitioned for peer discovery, signal broadcaster 212 may broadcast asignal to disparate wireless terminals within range (e.g., disparatewireless terminals 204-206). The signal may be utilized by disparatewireless terminals 204-206 to detect that wireless terminal 202 hasentered the network and/or determine an identity of wireless terminal202. Moreover, peer detector 214 may obtain broadcast signals fromdisparate wireless terminals 204-206, Peer detector 214 may analyze theobtained signals to detect disparate wireless terminals 204-206 and/oridentify disparate wireless terminals 204-206.

Peer discovery effectuated by peer discovery communicator 210 may bepassive. Further, peer discovery may be symmetric; thus, wirelessterminal 202 may detect and identify disparate wireless terminal 1 204and disparate wireless terminal 1 204 may detect and identify wirelessterminal 202. However, it is contemplated that a first wireless terminalmay detect and identify a second wireless terminal, but the secondwireless terminal may fail to detect and identify the first wirelessterminal. Moreover, the defined time interval utilized for peerdiscovery may be much shorter than the time between peer discoveryintervals. Additionally, upon detection and identification, furthercommunication (e.g., paging, traffic) between wireless terminal 202 anddisparate wireless terminal(s) 204-206 may, but need not, beeffectuated.

Referring to FIG. 3, illustrated is an example timing diagram 300utilized by synchronized peers communicating within a peer-to-peerenvironment. Timing diagram 300 may be partitioned with intervals forpeer discovery as well as intervals for differing functions such aspaging and communicating traffic. As noted above, peers may besynchronized with one another based upon a common clock reference; thus,the peers may have a common notion of timing diagram 300. Peer discoveryintervals 302 are illustrated. Each peer discovery interval 302 may havea duration of T₀. Peer discovery intervals 302 may be dedicated fordetecting and identifying peers. Further, the time between peerdiscovery intervals 302 may be T₁. Any number of paging and/or trafficintervals may be included during T₁ between adjacent peer discoveryintervals 302. The terminal may transition to a sleep mode (e.g., forpower saving) during T₁ interval, for example, when the terminal doesnot find any peer in the peer discovery interval or does not find anypeer of interest.

The amount of time allocated for peer discovery may be a small fractionof the overall time. For instance, the time (T₁) between peer discoveryintervals may be at least 5 times larger than the time (T₀) allotted foreach peer discovery interval 302. Pursuant to another example, the ratioof T₁ to T₀ may be 10, 50, 100, 200, 300, and so forth, According to afurther example, peer discovery intervals 302 may have a duration, T₀,on the order of 2 ms (e.g., around 10 ms, 50 ms, . . . ). By way offurther illustration, T, the time between peer discovery intervals, maybe on the order of a few seconds or 1 minute. Allocating a small portionof overall time for peer discovery provides efficient utilization ofpower, since peers not involved in communicating pages and/or trafficmay sleep during the time, T₁, in between each peer discovery interval302.

With reference to FIG. 4, illustrated is an example timing diagram 400of a peer discovery interval. The peer discovery interval may include anumber of possible transmission times during which a wireless terminalcan broadcast a signal. For instance, the peer discovery interval mayinclude N symbols (e.g., OFDM symbols), where N may be any integer.Further, each symbol may last 10 μs and N may be 50, 100, 200, etc.;however, the subject claims are not so limited. Each peer within apeer-to-peer network may transmit utilizing one or more of the symbols;the peer may listen to the remainder of the symbols to detect and/oridentify other peers within range. In accordance with an example, a peermay transmit on a first symbol at a first time and a second symbol at asecond time, where the first time and the second time may or may not becontiguous.

According to an example, the peer discovery interval may include 200symbols. In one or more embodiments, the 200 symbols may be used fortransmitting broadcast signals by the terminals. In other embodiments,every other symbol may be utilized for transmission (e.g., 100 symbolsmay be employed for transmission). Before the peer discovery interval,each wireless terminal that, wishes to engage in peer-to-peercommunication may select one or more transmission symbols (e.g., out ofthe total of 100 transmission symbols pursuant to the above example).During the selected symbol time(s), the wireless terminal transmits amessage to disparate wireless terminal(s) (e.g., peer(s)). The messagemay include one tone in one of the selected transmission symbols.Further, during at least a fraction of the remaining symbol times in thepeer discovery interval, the wireless terminal listens and decodes thetransmissions of the disparate wireless terminal(s). Since peer-to-peercommunication may employ a half-duplex mode, where a wireless terminaleither transmits or receives data at a particular time, the wirelessterminal may transmit for 10% of the transmission times and receive forthe remaining 90% of the time. By way of another example, the wirelessterminal may transmit 30% of the time and receive 70% of the time. Inaccordance with an illustration, the wireless terminal may determine thetransmission time(s) and/or the waveform (e.g., the frequency tonetransmitted in a selected transmission symbol) to transmit based upon anidentifier and/or a notion of time (e.g., derived from a receivedBeacon). The notion of time is in essence a time-varying variable. Allthe wireless terminals may get the same notion of time. For example, thewireless terminals may obtain a time-varying variable from the broadcast(e.g., beacon) signal from the base station. The time-varying variablecan be some variable transmitted in the broadcast signal. For example,the variable can be some time counter or system time, which varies overtime. In this document, the notion of time is referred to as timecounter. It is desired that the time counter varies from one peerdiscovery interval to another. By way of further example, the wirelessterminal may utilize a pseudo-random number generator, whose seed can bean identifier of the wireless terminal and a current counter valuesupplied by a broadcast signal from a base station, to selecttransmission time(s) and/or the waveform. As the time counter varies,the selected transmission symbol time(s) and/or waveform may also varyfrom one peer discovery interval to another.

Referring now to FIG. 5, illustrated is a system 500 that effectuatessynchronized communications over a peer-to-peer network. System 500includes wireless terminal 202 that may communicate via a peer-to-peernetwork with disparate wireless terminal(s) (e.g., peer(s)). Wirelessterminal 202 may include synchronizer 208 that coordinates performanceof various functions (e.g., peer discovery, paging, traffic).Synchronizer 208 may obtain and analyze a common clock reference todetermine a meaningful notion of time. Additionally, the disparatewireless terminal(s) may obtain and analyze the common clock referenceto yield the same notion of time; hence, peers within a local area maysynchronize with the same common clock reference (e.g., from the samebase station). Therefore, peers get the same timing (timingsynchronized) without directly communicating with each other. Forexample, the common clock reference may be a Beacon signal transmittedby a base station within range of wireless terminal 202 and the peers.Further, wireless terminal 202 may comprise peer discovery communicator210, which further includes signal broadcaster 212 and peer detector214.

Peer discovery communicator 210 may also include a signal generator 502that yields a message to be sent by signal broadcaster 212, According toan example, signal generator 502 may determine transmission time(s)within a peer discovery interval and/or waveform(s) to be transmitted.Signal generator 502 may yield transmission time(s) and/or waveform(s)of the message as a function of an identifier (ID) (e.g., correspondingto wireless terminal 202) and a time (e.g., determined from common clockreference). In accordance with an example, the message yielded by signalgenerator 502 may be a Beacon signal, which may provide powerefficiency; thus, signal generator 502 may effectuate transmitting aparticular tone on a selected OFDM symbol. It is contemplated that morethan one Beacon signal may be transmitted. Further, due to privacyissues, safeguards may be put into place to mitigate undesireddistribution of the ID of wireless terminal 202.

Pursuant to another example, signal generator 502 may provide signalbroadcaster 212 with an ID associated with wireless terminal 202 thatmay be broadcast to peer(s). Peer(s) obtaining the ID may detect andidentify wireless terminal 202 by utilizing the received ID. Forexample, the ID of wireless terminal 202 may be an output of an M-bithash function whose input is the plain-text name of wireless terminal202 and a current counter value supplied by a base station broadcastsignal (e.g., common clock reference, Beacon, . . . ). The countervalue, for instance, may be constant during a current peer discoveryinterval and may be decodable by ail peers. Further, the hash functionmay be specified a priori by a protocol and known to the peers.

By way of an example, peer detector 214 may maintain a list ofplain-text names, of buddy peers associated with wireless terminal 202.Further, upon decoding a particular ID, peer detector 214 may hash itsplain-text buddy names using the current, counter value. If at least oneof the output IDs matches the decoded ID, peer detector 214 may concludethat the corresponding buddy peer is present If no match is found orthere are multiple matches, peer detector 214 may be unable to concludeas to the presence of any buddy peers. Moreover, each peer may vary thenumber of bits, previously denoted by M, of the output of the IDgenerating hash function in order to ensure that it is eventuallydiscovered. A peer maintains a list of disparate wireless terminals thatare detected to be present in the current time. The list may include alldisparate wireless terminals or may include those In the predefinedbuddy list of wireless terminal 202 or the user who is using wirelessterminal 202. As the time goes by, the list evolves, because somedisparate wireless terminals may disappear (e.g., because thecorresponding users move away), or because other disparate wirelessterminals may appear (e.g., because the corresponding users move close).The peer may add the new disparate wireless terminals to the list ordelete disappearing disparate wireless terminals from the list. In anembodiment, the peer passively maintains the list. In this case, a firstpeer may detect the presence of a second peer and keep the second peerin its list without informing the second peer. As a result, the secondpeer may not know that the first peer has already kept the second peerin the list. By symmetry, depending on wireless channel and interferencecondition, the second peer may also detect the presence of the firstpeer and keep the first peer in its list without informing the firstpeer. In another embodiment, after the first peer detects the presenceof the second peer, the first peer proactively sends a signal to informthe second peer so that the second peer now knows that the first peerhas already kept the second peer in the list, even though the first peerhas no data traffic to communicate with the second peer yet. The firstpeer may selectively decide whether it sends a signal. For example, thefirst peer may send a signal only to another peer that is in thepredefined buddy list.

Wireless terminal 202 may also include a pager 504 and a trafficcommunicator 506. Based upon the synchronized notion of time yielded bysynchronizer 208, pager 504 and traffic communicator 506 may transmitand/or receive signals via the peer-to-peer network during respective,allocated times for such functions. Upon detecting and identifying apeer, pager 504 enables wireless terminal 202 to initiate communicationwith the peer. Further, during an allotted traffic interval, wirelessterminal 202 and the peer may transmit and/or receive traffic byemploying traffic communicator 506.

Wireless terminal 202 may additionally include a state transitioner 508.To provide power savings, state transitioner 508 may enable wirelessterminal 202 to enter a sleep state during time intervals associatedwith functions (e.g., paging, traffic) other than peer discovery whenwireless terminal 202 is not involved with such functions. Further,state transitioner 508 switches wireless terminal 202 to an on state(e.g., from a sleep state) during peer discovery intervals to enablewireless terminal 202 to discover peer(s) and/or be discovered bypeer(s).

Moreover, wireless terminal 202 may include memory 510 and a processor512. Memory 510 may retain an identifier associated with wirelessterminal 202. Further, memory 510 may include a list a buddy peers matmay be referenced by peer detector 214. Additionally, memory 510 mayretain instructions related to synchronizing time intervals fordiffering functions with disparate wireless terminals, establishing acommon period of time for peer discovery in a local area (e.g., basedupon information obtained from a base station), identifying location(s)within a peer discovery interval for broadcasting wireless terminalrelated signals, generating signals for transmission to disparatewireless terminals, detecting and/or identifying disparate wirelessterminals within range, and so forth. Moreover, processor 512 mayexecute instructions, described herein.

In accordance with an example, the peer-to-peer network may operate inthe same frequency band as the cellular network (e.g., wide areanetwork). In this case, peers may obey a transmit power cap in order tomitigate excessive interference caused for uplink cellular mobiles. Forexample, an open-loop power control may be utilized whereby wirelessterminal 202 may estimate its path gain to the base station by measuringa received power of a signal from the base station. Thus, each peer mayselect its transmit power under the constraint that the received powerat the base station is less than a certain threshold.

Since typical communication distances are on the order of meters fortens of meters) for peer-to-peer communication, the symbol duration canbe made significantly shorter as compared to cellular communicationbecause the delay spread may be shorter. Consequently, time divisionduplex (TDD) peer-to-peer communication can be accomplished with lessdelay than in a cellular system since the switching time betweentransmitting arid listening may be reduced. For example, the symbolduration may be 10 μs, with a cyclic prefix covering roughly 1 μs ofdelay spread.

Referring to FIG. 6, illustrated is an example time-frequency grid 600associated with transmission during a peer discovery interval. Thex-axis represents time and may include N symbols (e.g., where N may beany integer), and the y-axis represents frequency and may include Mtones (e.g., where M may be any integer). According to an example, awireless terminal may select a particular symbol (e.g., transmissiontime) for transmission (e.g., based upon an identifier of the wirelessterminal or the user who is using the wireless terminal and/or timecounter). Further, a particular tone corresponding to the selectedsymbol may be determined (e.g., based upon the identifier and/or time).Thus, the x and y coordinates (e.g., (x₁, y₁) within grid 600, asillustrated by the shading, may provide information (e.g., whenevaluated by a peer receiving such signal). By transmitting a singlesymbol, the alphabet employed by the wireless terminal may be log₂(M·N). According to a further example, more than one symbol may beutilized by the wireless; terminal for transmission: during the peerdiscovery interval. Pursuant to this example, the tones (e.g., Beacons)may be transmitted at different times. By way of illustration, if twoBeacons are transmitted with coordinates (x₁, y₁) and (x₂, y₂), x₁differs from x₂ to mitigate transmitting the two Beacons concurrently.

Referring to FIGS. 7-9, methodologies relating to performing peerdiscovery within a peer-to-peer network are illustrated. While, forpurposes of simplicity of explanation, the methodologies are shown anddescribed as a series of acts, it is to be understood and appreciatedthat the methodologies are not limited by the order of acts, as someacts may, in accordance with one or more embodiments, occur in differentorders and/or concurrently with other acts from that shown and describedherein. For example, those skilled in the art will understand andappreciate that a methodology could alternatively be represented as aseries of interrelated states or events, such as in a state diagram.Moreover, not all illustrated acts may be required to implement amethodology in accordance with one or more embodiments.

Turning to FIG. 7, illustrated is a methodology 700 that facilitatesoperating a wireless terminal in a peer-to-peer network. At 702, asignal may be received from a signal source (e.g., base station, anaccess node, a GPS satellite, . . .). The signal may be broadcast by abase station in a vicinity of the peer-to-peer network; thus, a wirelessterminal performing synchronization as well as other wireless terminals(e.g., that may similarly effectuate synchronization) in thepeer-to-peer network may obtain a common signal from the same basestation. Further, the signal may be a common clock reference. Pursuantto an example, the signal may be a Beacon, a PN (pseudo random) sequencesignal, a pilot signal, etc. Moreover, the signal may be periodicallyreceived.

At 704, time positions of a sequence of peer discovery intervals may bedetermined based upon the signal. Thus, a first wireless terminal maydetermine a first sequence of peer discovery intervals. Peer discoveryintervals may be synchronized between wireless terminals in apeer-to-peer network. For example, a second wireless terminal mayreceive the signal from the signal source and determine a secondsequence of peer discovery intervals based upon the signal, wherein thesecond sequence may substantially overlap with the first sequence intime. Timing information may be derived from the received signal.Moreover, since the same signal may be employed by differing wirelessterminals, the wireless terminals may have a common notion of time.Further, the common notion of time may be utilized to partition atimeline into distinct periods for differing types of functions (e.g.,peer discovery, paging, traffic). According to an example, the amount oftime mat separates two successive peer discovery intervals in thesequence may be at least 5 times larger than a duration of time ofeither of the successive peer discovery intervals. Pursuant to a furtherexample, the amount of time that separates two successive peer discoveryintervals in the sequence of peer discovery intervals may be at least100 times larger than the duration of time of either of the twosuccessive peer discovery intervals. Additionally, meaningfully definedpaging intervals and/or traffic intervals may be identified based uponthe received signal. In accordance with an example, a plurality ofpaging intervals and a plurality of traffic intervals may be positionedbetween adjacent peer discovery intervals. Moreover, a wireless terminalmay transition to an on state from a power saving state (e.g., sleepstate) before a peer discovery interval-starts (e.g., if the wirelessterminal lacks involvement in active traffic prior to the peer discoveryinterval). Also, the wireless terminal may switch to a power savingstate (e.g., sleep state) from an on state after a peer discoveryinterval ends (e.g., if the wireless terminal lacks involvement inactive traffic subsequent to the peer discovery interval).

Now referring to FIG. 8, illustrated is a methodology 800 thatfacilitates transmitting a message that enables peers to detect andidentify a wireless device in a peer-to-peer network. At 802, a signalmay be obtained from a signal source (e.g., base station, access node,GPS satellite, . . .). For example, a time may be derived from thesignal. Moreover, for instance, the base station may be associated witha wide area network, and a common spectrum ( e.g., licensed spectrum)may be shared between the wide area network and the peer-to-peernetwork. At 804, time positions of a sequence of peer discoveryintervals may be identified based upon the obtained signal. For example,timing of the sequence of peer discovery intervals maybe specified by apredetermined protocol commonly known within the peer-to-peer network(e.g., known by differing wireless terminals included in thepeer-to-peer network). Further, paging and/or traffic intervals may beidentified based upon the obtained signal. The partitioned intervals ofthe peer-to-peer network, for instance, may enable short range, highdata rate communication between peers.

At 806, at least one symbol within each of the peer discovery intervalsof the sequence may be selected based on an identifier and a timecounter variable derived from the signal. It is to be appreciated thatone or more symbols, which represent a first fraction of each peerdiscovery interval, may be selected. Moreover, the identifier may relateto a wireless terminal and/or a user currently utilizing the wirelessterminal It is contemplated that a position of the selected symbol(s)within a peer discovery interval may vary from one peer discoveryinterval to another. Additionally, a value of the time counter variablemay vary from one peer discovery interval to another. Further, selectionof symbol(s) may be effectuated prior to each peer discovery period andmay be specified by a protocol known across the peer-to-peer network.According to an example, each peer discovery period may include Nsymbols (e.g., OFDM symbols), where N is any integer. Further, each ofthe N symbols may correspond to a unique transmission time (e.g., eachsymbol may last 10 μs). Moreover, a half-duplex mode may be employedsuch that either transmission or reception occurs at each time, but notboth transmission and reception. According to an example, transmissiontime may be 10% of a duration of each peer discovery interval or less(e.g., and 90% of the duration may be utilized for listening). Pursuantto another example, the transmission time may account for 30% of theduration of each peer discovery interval, while 70% may be employed forreceiving. At 808, a single tone (e.g., message) may be broadcast oneach of the selected symbols. For example, the tone may be used to senda Beacon signal (e.g., to enhance efficiency). The frequency location ofthe tone may be determined based on the identifier and/or the timecounter variable. Additionally, the frequency location of the tone mayvary from one peer discovery interval to another in the sequence of peerdiscovery intervals. Also, a transmission power of the tone may be atleast 10 times higher than a transmission power of any other tone in thesame symbol. Further, if more than one Beacon is broadcast (e.g., fromone wireless terminal), different symbols may correspond to each of theBeacons.

With reference to FIG. 9, illustrated is a methodology 900 thatfacilitates detecting and identifying peers in a peer-to-peer network.At 902, a signal may be obtained from a signal source. At 904, timepositions of a sequence of peer discovery intervals may be identifiedbased upon the obtained signal. For example, the sequence may besynchronized in time, with a disparate sequence of peer discoveryintervals determined by a disparate wireless terminal. At 906, listeningmay occur during, a fraction of each of the peer discovery intervals.For example, listening may be effectuated for at least 70% of each peerdiscovery interval, while the remainder maybe employed for transmitting,According to another example, 90% or more of a peer discovery intervalmay be utilized by a wireless terminal for listening. Moreover, one ormore symbols selected for transmitting during each of the peer discoveryintervals may be excluded from the respective fraction for listeningassociated with each peer discovery interval. At 908, a broadcastmessage (e.g., signal) from a peer may be detected while listeningduring the fraction of a current peer discovery interval. For example,the broadcast message may be obtained at a time that differs fromtime(s) utilized for transmission by a receiving peer; thus, thefraction of the current peer discovery interval during which detectionoccurs may be distinct from a differing fraction of the current peerdiscovery interval employed for transmission. By way of furtherillustration, a tone and a symbol may be determined from the detectedbroadcast message. At 910, an identifier (e.g., of the peer and/or auser employing the peer) may be decoded from the broadcast message. Byway of illustration, the identifier may be decoded based upon a timecounter variable derived from the signal obtained from the signalsource.

The first fraction of each peer discovery interval mentioned in FIG. 8,which is used for transmitting a broadcast message, and the secondfraction of each peer discovery interval mentioned in FIG. 9, which isused for detecting broadcast messages from other terminals, do notoverlap in time. In an embodiment, the second traction is no less thanthe first fraction. In some cases, the second fraction may be 2, 4, 8,16, 50, etc. times larger than the first fraction.

According to an example, upon detecting the broadcast message of thepeer and decoding the corresponding identifier for the peer, suchidentifier may be added to a list of identifiers that representsdetected terminals. Pursuant to another example, a buddy list of buddyidentifiers may be retained in memory and the decoded identifier may becompared with the buddy identifiers in the buddy list; further, thedecoded identifier may be marked as one of the buddy identifiers if thecomparison result indicates that the detected identifier issubstantially similar to one of the buddy identifiers in the buddy list.Continuing this example, a signal may be transmitted to the peerassociated with the decoded identifier that, informs the peer that ithas been identified.

It will be appreciated that, in accordance with one or more aspectsdescribed herein, inferences can be made regarding discovering andidentifying peers in a peer-to-peer environment. As used herein, theterm to “infer” or “inference” refers generally to the process ofreasoning about or inferring states of the system, environment, and/oruser from a set of observations as captured via events and/or data.Inference can be employed to identify a specific context or action, orcan generate a probability distribution over states, for example. Theinference can be probabilistic—that is, the computation of a probabilitydistribution over states of interest based on a consideration of dataand events. Inference can also refer to techniques employed forcomposing higher-level events from a set of events and/or data. Suchinference results in the construction of new events or actions from aset of observed events and/or stored event data, whether or not theevents are correlated in close temporal proximity, and whether theevents and data come from one or several event and data sources.

According to an example, one or more methods presented above can includemaking inferences pertaining to synchronizing a peer discovery intervalfor utilization in connection with communicating via the peer-to-peernetwork. In accordance wife another example, an inference may be maderelated to estimating a common notion of time from a broadcast signal inthe peer-to-peer network. It will be appreciated that the foregoingexamples are illustrative in nature and are not intended to limit thenumber of inferences that can be made or the maimer in which suchinferences are made in conjunction with the various embodiments and/ofmethods described herein.

FIG. 10 depicts an example communication system 1000 implemented inaccordance with various aspects including multiple cells: cell I 1002,cell M 1004,: Note that neighboring cells 1002, 1004 overlap slightly,as indicated by cell boundary region 1068, thereby creating potentialfor signal interference between signals transmitted by base stations inneighboring cells. Each cell 1002, 1004 of system 1000 includes threesectors. Cells which have not be subdivided into multiple sectors (N=1),cells with two sectors (N=2) and cells with more than 3 sectors (N>3)are also possible in accordance with various aspects. Cell 1002 includesa first sector, sector I 1010, a second sector, sector II 1012, and a.third sector, sector III 1014. Each sector 1010, 1012, 1014 has twosector boundary regions; each boundary region is shared between twoadjacent sectors.

Sector boundary regions provide potential for signal interferencebetween signals transmitted by base stations in neighboring sectors.Line 1016 represents a sector boundary region between sector I 1010 andsector II 1012; line 1018 represents a sector boundary region betweensector II 1012 and sector III 1014; line 1020 represents a sectorboundary region between sector III 1014 and sector I 1010. Similarly,cell M 1004 includes a first sector, sector I 1022, a second sector,sector II 1024, and a third sector, sector III 1026. Line 1028represents a sector boundary region between sector I 1022 and sector II1024; line 1030 represents a sector boundary region between sector II1024 and sector III 1026; line 1032 represents a boundary region betweensector III 1026 and sector I 1022. Cell I 1002 includes a base station(BS), base station I 1006, and a plurality of end nodes (ENs) (e.g.,wireless terminals) in each sector 1010,1012,1014. Sector I 1010includes EN(1) 1036 and EN(X) 1038 coupled to BS 1006 via wireless links1040, 1042, respectively; sector II 1012 includes EN(1′) 1044 and EN(X′)1046 coupled to BS 1006 via wireless links 1048, 1050, respectively;sector III 1014 includes EN(1″) 1052 and EN(X″) 1054 coupled to BS 1006via wireless links 1056,1058, respectively. Similarly, cell M 1004includes base station M 1008, and a plurality of end nodes (ENs) in eachsector 1022, 1024, 1026. Sector I 1022 includes EN(1) 1036′ and EN(X)1038′ coupled to BS M 1008 via wireless links 1040′, 1042′,respectively; sector II 1024 includes EN(1′) 1044′ and EN(X′) 1046′coupled to BS M 1008 via wireless links 1048′. 1050′, respectively;sector 3 1026 includes EN(1″) 1052′ and EM(X″) 1054′ coupled to BS 1008via wireless links 1056′, 1058′, respectively.

System 1000 also includes a network node 1060 which is coupled to BS I1006 and BS M 1008 via network links 1062,1064, respectively. Networknode 1060 is also coupled to other network nodes, e.g., other basestations, AAA server nodes, intermediate nodes, routers, etc. and theInternet via network link 1066. Network links 1062, 1064, 1066 maybe,e.g., fiber optic cables. Each end node, e.g., EN(1) 1036 may be awireless terminal including a transmitter as well as a receiver. Thewireless terminals, e.g., EN(1) 1036 may move through system 1000 andmay communicate via wireless links with the base station in the cell inwhich the EN is currently located. The wireless terminals, (WTs), e.g.,EN(1) 1036, may communicate with peer nodes, e.g., other WTs in system1000 or outside system 1000 via a base station, e.g., BS 1006, and/ornetwork node 1060. WTs, e.g., EN(1) 1036 may be mobile communicationsdevices such as cell phones, personal data assistants with wirelessmodems, etc. Respective base stations perform tone subset allocationusing a different method for the strip-symbol periods, from the methodemployed for allocating tones and determining tone hopping in the restsymbol periods, e.g., non strip-symbol periods. The wireless terminalsuse the tone subset allocation method along with information receivedfrom the base station, e.g., base station slope ID, sector IDinformation, to determine tones that they can employ to receive data andinformation at specific strip-symbol periods. The tone subset allocationsequence is constructed, in accordance with various aspects to spreadinter-sector and inter-cell interference across respective tones.

Local area peer-to-peer communication may also be supported bycommunication system 1000. For example, a common spectrum may beutilized for both local-area peer-to-peer communication as well ascommunication via the wide area network (e.g., cellular infrastructurenetwork). Wireless terminals may communicate with other peers via alocal area peer-to-peer network such as peer-to-peer networks 1070,1072,and 1074. Although three peer-to-peer networks 1070-1074 are depicted,it is to be appreciated that any number, size, shape, etc. ofpeer-to-peer networks may be supported. For instance, each peer-to-peernetwork 1070-1074 may support transfer of signals directly betweenwireless terminals. Further, each peer-to-peer network 1070-1074 mayinclude wireless terminals within a similar geographic area (e.g.,within range of one another). For example, EN( ) 1036 may communicatewith EN(X) 1038 by way of the local area peer-to-peer network 1070.However, it is to be appreciated that wireless terminals need not beassociated with the same sector and/or cell to be included in a commonpeer-to-peer network. Further, peer-to-peer networks may overlap (e.g.,EN(X′) 1046 may leverage peer-to-peer networks 1072 and 1074).Additionally, a wireless terminal may not be supported by a peer-to-peernetwork. Wireless terminals may employ the wide area network and/or thepeer-to-peer network where such networks overlap (e.g., concurrently orserially). Moreover, wireless terminals may seamlessly switch orConcurrently leverage such networks. Accordingly, wireless terminalswhether transmitting and/or receiving may selectively employ one or moreof the networks to optimize communications.

FIG. 11 illustrates an example base station 1100 in accordance withvarious aspects. Base station 1100 implements tone subset allocationsequences, with different tone subset allocation sequences generated forrespective different sector types of the cell. Base station 1100 may beused as any one of base stations 1006, 1008 of the system 1000 of FIG.10. The base station 1100 includes a receiver 1102, a transmitter 1104,a processor 1106, e.g., CPU, an input/output interface 1108 and memory1110 coupled together by a bus 1109 over which various elements 1102,1104, 1106, 1108, and 1110 may interchange data arid information.

Sectorized antenna 1103 coupled to receiver 1102 is used for receivingdata and other signals, e.g., channel reports, from wireless terminalstransmissions from each sector within the base station's cell.Sectorized antenna 1105 coupled to transmitter 1104 is used fortransmitting data and other signals, e.g., control signals, pilotsignal, beacon signals, eta to wireless terminals 1200 (see FIG. 12)within each sector of the base station's cell. In various aspects, basestation 1100 may employ multiple receivers 1102 and multipletransmitters 1104, e.g., an Individual receiver 1102 for each sector andan individual transmitter 1104 for each sector. Processor 1106, may be,e.g., a general purpose central processing unit (CPU). Processor 1106controls operation of base station 1100 under direction of one or moreroutines 1118 stored in memory 1110 and implements the methods. I/Ointerface 1108 provides a connection to other network nodes, couplingthe BS 1100 to other base stations, access routers, AAA server nodes,etc., other networks, and the Internet. Memory 1110 includes routines1118 and data/information 1120.

Data/Information 1120 includes data 1136, tone subset allocationsequence information 1138 including downlink strip-symbol timeinformation 1140 and downlink tone information 1142, and wirelessterminal (WT) data/info 1144 including a plurality of sets of WTinformation: WT 1 info 1146 and WT N info 1160. Each set of WT info,e.g., WT 1 info 1146 includes data 1148, terminal ID 1150, sector ID1152, uplink channel information 1154, downlink channel information1156, and mode information 1158.

Routines 1118 include communications routines 1122 and base stationcontrol routines 1124. Base station control routines 1124 includes ascheduler module 1126 and signaling routines 1128 including a tonesubset allocation routine 1130 for strip-symbol periods, other downlinktone allocation hopping routine 1132 for the rest of symbol periods,e.g., non strip-symbol periods, and a beacon routine 1134.

Data 1136 includes data to be transmitted that will be sent to encoder1114 of transmitter 1104 for encoding prior to transmission to WTs, andreceived data from WTs that has been processed through decoder 1112 ofreceiver 1102 following reception. Downlink strip-symbol timeinformation 1140 includes the frame synchronization structureinformation, such as the superslot, beaconslot, and ultraslot structureinformation and information specifying whether a given symbol period isa strip-symbol period, and if so, the index of the strip-symbol periodand whether the strip-symbol is a resetting point to truncate the tonesubset allocation sequence used by the base station. Downlink toneinformation 1142 includes information including a carrier frequencyassigned to the base station 1100, the number and frequency of tones,and the set of tone subsets to be allocated to the strip-symbol periods,and other cell and sector specific values such as slope, slope index andsector type.

Data 1148 may include data that WT1 1200 has received from a peer node,data that WT 1 1200 desires to be transmitted to a peer node, anddownlink channel quality report feedback information. Terminal ID 1150is a base station 1100 assigned ID that identifies WT 1 1200. Sector ID1152 includes information identifying the sector in which WT1 1200 isoperating. Sector ID 1152 can be used, for example, to determine tiresector type. Uplink channel information 1154 includes informationidentifying channel segments that have been allocated by scheduler 1126for WT1 1200 to use, e.g., uplink traffic channel segments for data,dedicated uplink control channels for requests, power control, timingcontrol, etc. Each uplink channel assigned to WT1 1200 Includes one ormore logical tones, each logical tone following an uplink hoppingsequence. Downlink channel information 1156 includes informationidentifying channel segments that have been allocated by scheduler 1126to carry data and/or information to WT1 1200, e.g., downlink trafficchannel segments for user data. Each downlink channel assigned to. WT11200 includes one or more logical tones, each following a downlinkhopping sequence. Mode information 1158 includes information identifyingthe state of operation of WT1 1200, e.g. sleep, hold, on.

Communications routines 1122 control the base station 1100 to performvarious communications operations and implement various communicationsprotocols. Base station control routines 1124 are used to control thebase station 1100 to perform basic base station functional tasks, e.g.,signal generation and reception, scheduling, and to implement, the stepsof the method of some aspects including transmitting signals to wirelessterminals using the tone subset allocation sequences during thestrip-symbol periods.

Signaling routine 1128 controls the operation of receiver 1102 with itsdecoder 1112 and transmitter 1104 with its encoder 1114. The signalingroutine 1128 is responsible for controlling the generation oftransmitted data 1136 and control information. Tone subset allocationroutine 1130 constructs the tone subset to be used in a strip-symbolperiod using the method of the aspect and using data/information 1120including downlink strip-symbol time info 1140 and sector ID 1152, Thedownlink tone subset allocation sequences will be different for eachsector type in a ceil and different for adjacent cells. The WTs 1200receive the signals in the strip-symbol periods in accordance with thedownlink tone subset allocation sequences; the base station 1100 usesthe same downlink tone subset allocation sequences in order to generatethe transmitted signals. Other downlink tone allocation hopping routine1132 constructs downlink tone hopping sequences, using informationincluding downlink tone information 1142, and downlink channelinformation 1156, for the symbol periods other than the strip-symbolperiods. The downlink data tone hopping sequences are synchronizedacross the sectors of a cell. Beacon routine 1134 controls thetransmission of a beacon signal, e.g., a signal of relatively high powersignal concentrated on one or a few tones, which may be used forsynchronization purposes, e.g., to synchronize the frame timingstructure of the downlink signal and therefore the tone subsetallocation sequence with respect to an ultra-slot boundary.

FIG. 12 illustrates an example wireless terminal (e.g., end node, mobiledevice, . . . ) 1200 which can be used as any one of the wirelessterminals (e.g., end nodes, mobile devices, . . . ), e.g., EN(1) 1036,of the system 1000 shown in FIG. 10. Wireless terminal 1200 implementsthe tone subset allocation sequences. Wireless terminal 1200 includes areceiver 1202 including a decoder 1212, a transmitter 1204 including anencoder 1214, a processor 1206, and memory 1208 which are coupledtogether by a bus 1210 over which the various elements 1202, 1204, 1206,1208 can interchange data and information. An antenna 1203 used forreceiving signals from a base station 1100 (and/or a disparate wirelessterminal) is coupled to receiver 1202. An antenna 1205 used fortransmitting signals, e.g.,. to base station 1100 (and/or a disparatewireless terminal) is coupled to transmitter 1204.

The processor 1206 (e.g., a CPU) controls operation of wireless terminal1200 and implements methods by executing routines 1220 and usingdata/information 1222 in memory 1208.

Data/information 1222 includes user data 1234, user information 1236,tone subset allocation sequence information 1250, and a buddy peer list1256. User data 1234 may include data, intended for a peer node, whichwill be routed to encoder 1214 for encoding prior to transmission bytransmitter 1204 to base station 1100, and data received from the basestation 1100 which has been processed by the decoder 1212 in receiver1202. User information 1236 includes uplink channel information 1238,downlink channel information 1240, terminal ID information 1242, basestation ID information 1244, sector ID information 1246, and modeinformation 1248. Uplink channel information 1238 includes informationidentifying uplink channels segments that have been assigned by basestation 1100 for wireless terminal 1200 to use when transmitting to thebase station 1100. Uplink channels may include uplink traffic channels,dedicated uplink control channels, e.g., request channels, power controlchannels and timing control channels, Each uplink channel includes oneor more logic tones, each logical tone following an uplink tone hoppingsequence. The uplink hopping sequences are different between each sectortype of a cell and between adjacent ceils. Downlink channel information1240 includes information identifying downlink channel segments thathave been assigned by base station 1100 to WT 1200 for use when BS 1100is transmitting data/information to WT 1200. Downlink channels mayinclude downlink traffic channels and assignment channels, each downlinkchannel including one or more logical tone, each logical tone followinga downlink hopping sequence, which is synchronized between each sectorof the cell.

User Info 1236 also includes terminal ID information 1242, which is abase station 1100 assigned identification, base station ID information1244 which identifies the specific base station 1100 that WT hasestablished communications with, and sector ID info 1246 whichidentifies the specific sector of the cell where WT 1200 is presentlylocated. Base station ID 1244 provides a cell slope value and sector IDinfo 1246 provides a sector index type; the cell slope value and sectorindex type may be used to derive tone hopping sequences. Modeinformation 1248 also included in user info 1236 identifies whether theWT 1200 is in sleep mode, hold mode, or on mode.

Tone subset allocation sequence information 1250 includes downlinkstrip-symbol time information 1252 and downlink tone information 1254.Downlink strip-symbol time information 1252 include the framesynchronization structure information, such as the superslot,beaconslot, and ultraslot structure information and informationspecifying whether a given symbol period is a strip-symbol period, andif so, the index of the strip-symbol period and whether the strip-symbolis a resetting point to truncate the tone subset allocation sequenceused by the base station. Downlink tone info 1254 includes informationincluding a carrier frequency assigned to the base station 1100, thenumber and frequency of tones, and the set of tone subsets to beallocated to the strip-symbol periods, and other cell and sectorspecific values such as slope, slope index and sector type.

Routines 1220 include communications routines 1224, wireless terminalcontrol routines 1226, synchronization routines 1228, signalgeneration/broadcast routines 1230, and detection routines 1232.Communications routines 1224 control the various communicationsprotocols used by WT 1200, For example, communications routines 1224 mayenable communicating via a wide area network (e.g., with base station1100) and/or a local area peer-to-peer network (e.g., directly withdisparate wireless terminal(s)). By way of further example,communications routines 1224 may enable receiving a broadcast signal(e.g., from base station 1100). Wireless terminal control routines 1226control basic wireless terminal 1200 functionality including the controlof the receiver 1202 and transmitter 1204. Synchronization routines 1228control synchronizing wireless terminal 1200 to a received signal (e.g.,from base station 1100). Peers within a peer-to-peer network may also besynchronized to the signal. For example, the received signal may be aBeacon, a PN (pseudo random) sequence signal, a pilot signal, etc.Further, the signal may be periodically obtained and a protocol (e.g.,associated with synchronization routines 1228) also known to peers maybe utilized to identify intervals corresponding to distinct functions(e.g., peer discovery, paging, traffic). Signal generation/broadcastroutines 1230 control creating a message for transmission during anidentified peer discovery interval A symbol and/or tone associated withthe message may be selected based upon a protocol (e.g., associated withsignal generation/broadcast routines 1230). Moreover, signalgeneration/broadcast routines 1230 may control sending the message topeers within the peer-to-peer network. Detection routines 1232 controldetection and identification of peers based upon messages receivedduring an identified peer discovery interval. Further, detectionroutines 1232 may identify peers based at least in part upon informationretained in buddy peer list 1256.

With reference to FIG. 13, illustrated is a system 1300 that enablessynchronizing a time period for discovery of peers in a peer-to-peernetwork. For example, system 1300 may reside at least partially within awireless terminal. It is to be appreciated that system 1300 isrepresented as including functional blocks, which may be functionalblocks that represent functions implemented by a processor, software, orcombination thereof (e.g., firmware:). System 1300 includes a logicalgrouping 1302 of electrical components that can act in conjunction. Forinstance, logical grouping 1302 may include an electrical component forreceiving a signal from a signal source 1304. Pursuant to anillustration, the signal source may be a base station, an access point,a GPS satellite, and so forth. For example, the signal may be broadcastto the peer-to-peer network. Moreover, the peers may obtain a commonnotion of time based upon the received signal. Further, logical grouping1302 may comprise an electrical component for locating time positions ofa sequence of peer discovery intervals based upon the signal 1306. Alength of time for each of the peer discovery intervals, for instance,may be at least 5 times smaller than a length of time between twoneighboring peer discovery intervals. Further, a subset of potentialtransmission times from the peer discovery interval may be selected fortransmission (e.g., based upon a time derived from the received signaland/or an identifier), for example. Moreover, the transmitted messagemay be utilized for detection and/or identification. Additionally,system 1300 may include a memory 1308 that retains instructions forexecuting functions associated with electrical components 1304 and 1306.While shown as being external to memory 1308, it is to be understoodthat one or more of electrical components 1304 and 1306 may exist withinmemory 1308.

It is to be understood that the embodiments described herein may beimplemented in hardware, software, firmware, middleware, microcode, orany combination thereof. For a hardware implementation, the processingunits may be implemented within one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described herein, or a combination thereof.

When the embodiments are implemented in software, firmware, middlewareor microcode, program code or code segments, they may be stored in amachine-readable medium, such as a storage component. A code segment mayrepresent a procedure, a function, a subprogram, a program, a routine, asubroutine, a module, a software package, a class, or any combination ofinstructions, data structures, or program statements. A code segment maybe coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters, or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted using any suitable means including memorysharing, message passing, token passing, network, transmission, etc.

For a software implementation, the techniques described herein may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes may be storedin memory units and executed by processors. The memory unit may beimplemented within the processor or external to the processor, in whichcase it can be communicatively coupled to the processor via variousmeans as is known in the art.

What has been described above includes examples of one or moreembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the aforementioned embodiments, but one of ordinary skill inthe art may recognize that many further combinations and permutations ofvarious embodiments are possible. Accordingly, the described embodimentsare intended to embrace all such alterations, modifications andvariations that fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim.

1. A method of operating a first wireless terminal in a peer-to-peernetwork, comprising: receiving a first signal from a signal sourcewherein the signal source is at least one of a base station, an accessnode, or a GPS satellite; and determining time positions of a firstsequence of peer discovery intervals based upon the received firstsignal.
 2. The method of claim 1, wherein the first signal is one of aBeacon, a PN (pseudo random) sequence signal, or a pilot signal.
 3. Themethod of claim 2, further comprising periodically receiving the firstsignal from the signal source.
 4. The method of claim 2, furthercomprising operating a second wireless terminal to receive the firstsignal from the signal source and to determine a second sequence of peerdiscovery intervals wherein the second sequence substantially overlapswith the first sequence in time.
 5. The method of claim 4, whereindetermination of the first sequence of peer discovery intervals is basedon a predetermined protocol commonly known by both the first and thesecond wireless terminals.
 6. The method of claim 1, wherein an amountof time that separates two successive peer discovery intervals in thefirst sequence of peer discovery intervals is at least 5 times largerthan a duration of time of either of the two successive peer discoveryintervals.
 7. The method of claim 6, wherein an amount of time thatseparates two successive peer discovery intervals in the first sequenceof peer discovery intervals is at least 100 times larger than theduration of time of either of the two successive peer discoveryintervals.
 8. The method of claim 1, further comprising: transitioningto an on state from a power saving state before a peer discoveryinterval starts; and switching to the power saving state from the onstate after the peer discovery interval ends.
 9. The method of claim 1,further comprising: selecting at least one symbol within each of thepeer discovery intervals of the first sequence based on a firstidentifier of either the first wireless terminal or a user currentlyusing the first wireless terminal and a time counter variable derivedfrom the first signal; and broadcasting a second signal on each of theselected symbols.
 10. The method of claim 9, further comprising:listening during a fraction of each of the peer discovery intervals;detecting a third broadcast signal from a peer while listening duringthe fraction of a current, peer discovery interval; and decoding asecond identifier from the third broadcast signal if it is determinedthat the third broadcast signal is present.
 11. The method of claim 10,wherein the second identifier is decoded based on the time countervariable.
 12. The method of claim 10, wherein the at least one selectedsymbol is excluded from the fraction of each of the peer discoveryintervals for listening.
 13. The method of claim 10, wherein the atleast one symbol selected for broadcasting the second signal within eachof the peer discovery intervals corresponds to less than 30% of aduration of each of the peer discovery intervals and wherein thefraction for listening corresponds to at least 70% of the duration ofeach of the peer discovery intervals.
 14. The method of claim 10,further comprising: adding the decoded second identifier to a first listof identifiers wherein the first list of identifiers represents detectedterminals.
 15. The method of claim 10, further comprising: storing asecond list of buddy identifiers; comparing the decoded secondidentifier with buddy identifiers in the second list of buddyidentifiers; and marking the decoded second identifier as a particularone of the buddy identifiers if the comparison result indicates that thedecoded second identifier is substantially similar to the particular oneof the buddy identifiers in the second list of buddy identifiers. 16.The method of claim 15, further comprising: transmitting a signal to thepeer associated with the decoded second identifier; and informing thepeer that it has been identified.
 17. The method of claim 9, wherein thevalue of the time counter variable varies from one peer discoveryinterval to another in the first sequence of peer discovery intervalsand a position of the at least one selected symbol within each of thepeer discovery intervals varies from one peer discovery interval toanother.
 18. The method of claim 17, wherein the second signal includesa tone.
 19. The method of claim 18, wherein a frequency location of thetone is selected based on the first identifier and the time countervariable and the frequency location of the tone varies from one peerdiscovery interval to another in the first sequence of peer discoveryintervals.
 20. The method of claim 18, wherein a transmission power ofthe tone is at least 10 times higher than a transmission power of anyother tone in the same symbol.
 21. A wireless communications apparatus,comprising: a memory that retains instructions related to obtaining afirst signal from a signal source and identifying time positions of afirst, sequence of peer discovery intervals based upon the obtainedfirst signal; and a processor, coupled to the memory, configured toexecute the instructions retained in the memory.
 22. The wirelesscommunications apparatus of claim 21, wherein the first signal isperiodically received and is one of a beacon signal, a PN (pseudorandom) sequence signal, or a pilot signal.
 23. The wirelesscommunications apparatus of claim 21, wherein a second wireless terminalreceives the first signal from the signal source and determines a secondsequence of peer discovery intervals wherein the second sequencesubstantially overlaps with the first sequence in time.
 24. The wirelesscommunications apparatus of claim 23, wherein tile memory furtherretains instructions for determining the first sequence of peerdiscovery intervals based on a predetermined protocol commonly knownwith the second wireless terminal.
 25. The wireless communicationsapparatus of claim 21, wherein the memory further retains instructionsfor separating two successive peer discovery intervals in the firstsequence by an amount of time at least 5 times a length of time ofeither of the two successive peer discovery intervals.
 26. The wirelesscommunications apparatus of claim 21, wherein the memory further retainsinstructions for transitioning to and from an on state before a start ofa peer discovery interval and after attend of the peer discoveryinterval, respectively.
 27. The wireless communications apparatus ofclaim 21, wherein the memory further retains instructions for selectingat least one symbol within each of the peer discovery intervals of thefirst sequence based on a first identifier and a time counter variablederived from the first signal, and broadcasting a second signal on eachof the selected symbols.
 28. The wireless communications apparatus ofclaim 27, wherein the memory further retains instructions for listeningduring a fraction of each of the peer discovery intervals, detecting athird broadcast signal from a peer during the fraction of a current peerdiscovery interval employed for listening, and decoding a secondidentifier from the third broadcast signal when detected.
 29. Thewireless communications apparatus of claim 28, wherein the memoryfurther retains instructions for decoding the second identifier based onthe time counter variable.
 30. The wireless communications apparatus ofclaim 28, wherein the memory further retains instructions for excludingthe at least one selected symbol from the listening related fraction ofeach of the peer discovery intervals.
 31. The wireless communicationsapparatus of claim 28, wherein the memory further retains instructionsfor broadcasting less than 30% of a duration of each of the peerdiscovery intervals and listening for the remainder of each duration.32. The wireless communications apparatus of claim 28, wherein thememory further retains instructions for adding the decoded secondidentifier to a first list of identifiers that represents detectedterminals.
 33. The wireless communications apparatus of claim 28,wherein the memory further retains a second list of buddy identifiersand instructions for comparing the decoded second identifier with buddyidentifiers in the second list and identifying the decoded, secondidentifier as a particular one of the buddy identifiers when the decodedsecond identifier is substantially similar to the particular one of thebuddy identifiers in the second list.
 34. The wireless communicationsapparatus of claim 27, wherein the memory further retains instructionsfor varying the time counter variable between peer discovery intervalsin the first sequence and varying a position of the at least oneselected symbol within each of the peer discovery intervals from onepeer discovery interval to another.
 35. The wireless communicationsapparatus of claim 34, wherein the memory further retains instructionsfor choosing a frequency location of a tone included in the secondsignal on a per peer discovery interval basis as a function of the firstidentifier and the time counter variable.
 36. A wireless communicationsapparatus that enables synchronizing a time period for discovery ofpeers in a peer-to-peer network, comprising: means for receiving a firstsignal from a signal source; and means for locating time positions of afirst sequence of peer discovery intervals based upon the first signal.37. The wireless communications apparatus of claim 36, furthercomprising means for periodically receiving the first signal, whereinthe first signal is one of a beacon signal, a PN (pseudo random)sequence signal or a pilot signal.
 38. The wireless communicationsapparatus of claim 36, further comprising means for synchronizing thefirst sequence of peer discovery intervals with a second sequence ofpeer discovery intervals located by a peer.
 39. The wirelesscommunications apparatus of claim 36, further comprising means forseparating successive peer discovery intervals in the first sequence bya time that is at least 5 times as long as a duration of each of thesuccessive peer discovery intervals.
 40. The wireless communicationsapparatus of claim 36, further comprising means for switching to andfrom a power saving state after an end of or before a beginning of apeer discovery interval, respectively.
 41. The wireless communicationsapparatus of claim 36, further comprising: means for selecting at leastone symbol within each of the peer discovery intervals of the firstsequence based on a first identifier and a time counter variable derivedfrom the first signal; and means for transmitting a broadcast, of asecond signal on each of the selected symbols.
 42. The wirelesscommunications apparatus of claim 41, further comprising: means forlistening during a fraction of each of the peer discovery intervals;means for detecting a third broadcast signal from a peer during thefraction of a present peer discovery interval employed for listening;and means for decoding a second identifier from the third broadcastsignal when detected based on the time counter variable.
 43. Thewireless communications apparatus of claim 42, further comprising meansfor enforcing a maximum percentage of a duration of each of the peerdiscovery intervals utilized for transmitting the broadcast on theselected symbols.
 44. The wireless communications apparatus of claim 41,further comprising: means for varying the time counter variable from onepeer discovery interval to the next; means for varying a position of theat least one selected symbol within each of the peer discovery intervalsfrom one peer discovery interval to another; and means for selecting afrequency location of a tone included in the second signal on a per peerdiscovery interval basis as a function of the first identifier and thevarying time counter variable.
 45. A machine-readable medium havingstored thereon machine-executable instructions for: obtaining a firstsignal from a base station; and determining time positions of a sequenceof peer discovery intervals as a function of the obtained first signal,the sequence being synchronized with disparate sequences of peers in apeer-to-peer network based upon the obtained signal.
 46. Themachine-readable medium of claim 45, the machine-executable instructionsfurther comprise periodically receiving the first signal, wherein thefirst signal is one of a beacon signal, a PN (pseudo random) sequencesignal or a pilot signal.
 47. The machine-readable medium of claim 45,the machine-executable instructions further comprise separatingsuccessive peer discovery intervals in the sequence by a duration thatis at least 5 times as long as a length of time of each of thesuccessive peer discovery intervals.
 48. The machine-readable medium ofclaim 45, the machine-executable instructions further comprise selectingat least one symbol within each of the peer discovery intervals of thesequence based on a first identifier and a time counter variable derivedfrom the first signal, and broadcasting a second signal on each of theselected symbols.
 49. The machine-readable medium of claim 48, themachine-executable instructions further comprise listening during afraction of each of the peer discovery intervals, detecting a thirdbroadcast signal from a peer during the fraction of a current peerdiscovery interval employed for listening, and decoding a secondidentifier from the third broadcast signal when detected.
 50. In awireless communication system, an apparatus comprising: a processorconfigured to: obtain a periodic signal from a base station; andidentify time positions of a sequence of peer discovery intervals basedupon the obtained periodic signal, wherein the sequence of peerdiscovery intervals is synchronized between peers of a peer-to-peernetwork.